Most people find that this is actually helpful, though, because signing up for (or using, since the vast majority of folks already have one) a Live ID enables a bunch of convenient features like easily uploading your photos and videos (either to Microsoft's services or to Flickr, YouTube, Facebook, etc.) And most users who use Movie Maker also want to, for instance, organize their photos. Let's not forget that iLife also comes as a suite for a reason.
On the other hand, signing up for a new throwaway account just to trash Microsoft... yeah, that's classy.
(Usual disclosure: I work at Microsoft.)